WO2005113971A1

WO2005113971A1 - Method for dosing a substance, use of said method and associated device

Info

Publication number: WO2005113971A1
Application number: PCT/EP2005/052099
Authority: WO
Inventors: Gerhard FRÄNKLE; Klaus Schrewe
Original assignee: Hjs Fahrzeugtechnik Gmbh & Co Kg
Priority date: 2004-05-19
Filing date: 2005-05-10
Publication date: 2005-12-01
Also published as: DE102004025327A1; DE112005000859A5

Abstract

The invention relates to a method for dosing a substance (2), in particular micro amounts for supplying said substances to an operating machine, e.g. an internal combustion engine. According to said method, the substance (2) to be dosed is converted into its gaseous aggregate state. Said method is characterised in that the substance (2) is liquefied before being converted into its gaseous aggregate state and said conversion is achieved by additional heating in order for the substance to be dosed. The invention also relates to a device for dosing a substance, comprising a reactor (1) for provisioning the substance (2) that exists in its solid form. The substance (2) is converted into its gaseous phase in said reactor (1).

Description

Process for dosing a substance, use of the process and device

The invention relates to a method for dosing a substance, in particular small quantities thereof, for feeding the same to a machine in operation, for example an internal combustion engine, in which method the substance to be dosed is brought into its gaseous state. Furthermore, the invention relates to a preferred use of the method and a device for metering a substance, comprising a reactor for storing the substance in its solid state, in which reactor the substance is brought into its gas phase.

Such methods are used, for example, in order to be able to introduce an additive into the combustion process in an internal combustion engine. Additives are introduced into the combustion process of internal combustion engines in order to optimize the combustion process. In diesel internal combustion engines, additives are integrated into the combustion process so that the soot particles produced when the diesel fuel is burnt have a lower flash point than unadditized combustion. In addition to additives which are fed into the combustion chamber in liquid form via the fuel, methods are also known in which the additive in its gaseous state is fed to the combustion chamber via the air to be fed to the combustion chamber. Gaseous ferrocene, for example, is used as the gaseous additive, as is proposed in EP 0 543 477 B1. In the process described in this document, the sublimation of ferrocene, which is already in its solid state of aggregation, is used at relatively low temperatures in order to feed the ferrocene, which is brought into its gas phase from its solid state, to the combustion chamber as a result of the vapor pressure. To achieve this, a ^{temperature of} 20 ^C C to max. 175 ° C preheated carrier gas stream in a ferrocene in its solid aggregate containing sublimator, so that with appropriate pressure and temperature values in the area of the coexistence line between the solid and gaseous phase through the Sublimation formed ferrocene gas is added as an additive in the carrier gas stream and is fed with this to the Verreπnungsraum. The air sucked in during operation of the internal combustion engine serves as carrier gas flow. Thus, the additive present in the gas phase is initially added to the intake air and supplied together with it to the combustion chamber of the internal combustion engine, so that the additive / offset air combined with the fuel, for example the diesel fuel, represents the additive-laden fuel-air mixture.

In this previously known method for loading a fuel-air mixture to be supplied to a combustion chamber of an internal combustion engine with an additive, namely ferrocene, a carrier gas stream is required to cause sublimation and to transport the ferocene converted into its gas phase. Since this is typically the air drawn in during operation of the internal combustion engine, the transport of the additive is dependent on the operation of the internal combustion engine. In cold ambient conditions, when the engine is started to supply the additive as intended, it is necessary to heat the carrier gas stream with an additional heating device, at least until the waste heat of the diesel engine can be used to heat the carrier gas stream. Differences in temperature in the carrier gas stream result in different sublimation rates, so that an exact and, above all, sufficient metering of the additive to be fed to the combustion chamber can only be approximated.

Proceeding from this discussed prior art, the invention is therefore based on the object of developing the method mentioned at the outset and the device mentioned at the outset in such a way that the method and the device allow more precise metering, especially of the smallest amounts of the gaseous substance to the one in operation Machine can be made.

According to the invention, the process-related problem is solved by a method mentioned at the outset, in which the substance is liquefied before being converted into its gaseous state before it is ner dosage is brought into its gaseous state in the course of further heating.

In this method, the substance, for example in its solid state, such as solid ferrocene, if the substance is intended as an additive for supplying it to the combustion chamber of an internal combustion engine, is heated by an appropriately designed heating device to the extent that it liquefies and in this way for example, additive liquid formed is brought above its boiling point in order to convert the additive into its gaseous state. With this measure, if desired, a sufficient overpressure can be generated in a reactor so that the additive gas generated can in principle be easily introduced into the combustion chamber of the internal combustion engine due to the pressure prevailing in the reactor. For better mixing, however, the additive gas generated is expediently introduced into a line supplying a gas to the combustion chamber, for example into the air intake line. The immediate heating of the additive, which is stored in its solid state, for liquefaction and subsequent evaporation thereof can be implemented with simple means. The operation of a reactor containing the additive in solid form, in which the described heating process results in an internal pressure above the ambient pressure after the heating device has been started up for the first time, enables a very precise metering of the additive gas generated. The heating device is advantageously operated to liquefy and evaporate the additive in such a way that a largely constant internal pressure is maintained in the reactor. A rod-shaped radiator which extends into the additive in solid form can be provided as the heating device. Since the amount of additive required is only small, this heater does not necessarily have to liquefy all of the additive stored in solid form, but it is sufficient if only a part of it is liquefied and kept liquid, from which liquefied additive the additive gas evaporates becomes. Such a heating device expediently extends into the area of the outlet of the reactor in which a throttle device for metering the outflowing additive gas is arranged. If necessary, with a Additive gas which cools back from its gas phase to its solid form can in principle completely or partially block a metering device, such as a throttle or a clock valve. When the heating device is started up again, this regressed additive is readily converted back into its gas phase by the adjacent arrangement of such a metering device for the heating device, so that such condensation phenomena, particularly on the elements critical for metering, do not impair the desired flow of the additive gas into the combustion chamber of the internal combustion engine ,

In a preferred embodiment of the method, it is provided that the substance for the metering process is converted from its liquid state of matter into its gaseous state of matter by supplying heat using at least one electric heating element, and a dosage is controlled by the amount of the gaseous substance produced in each case,

- by keeping the substance in its liquid state at boiling temperature,

- Using a defined heat storage capacity of the radiator, the at least one heating element, which also has the temperature of the liquid substance, is heated depending on the current flow parameters by a defined amount of heat above the boiling point of the substance and

the defined heat fed into the radiator and / or its heat store is transferred by heat conduction to the substance which is at the boiling point and thereby a quantity of the substance which is proportional to the quantity of heat transferred is converted into its gaseous state,

- The amount of substance brought into the gaseous state is a dose of the substance to be fed to the machine in operation.

The device-related object is achieved by a device having the features of claim 12.

In the method of the aforementioned preferred embodiment and The same applies to the claimed device, metering is carried out by actuating at least one electric radiator, transferring the heat generated to the substance in its liquid state and generating the amount of the gaseous substance, for example gaseous ferrocene, which is generated in proportion to the heat transferred. In this process, the substance from which the gaseous substance is to be produced is kept at its boiling point in its liquid state. A defined amount of heat is transferred to the material by heat conduction by means of a contact heating element which is arranged within the material in its liquid state and is kept at the boiling temperature or which extends into the liquid material. The heat storage capacity of the radiator is used to define the amount of heat transferred to the liquid substance. Since the heating of a radiator is known via the characteristic curve of the radiator and its mass in accordance with the current supply parameters present, a defined amount of heat can be introduced into the radiator or its heat store via the parameters of the control of the radiator.

The introduction of a defined amount of heat to evaporate the desired amount of substance from the boiling liquid bath can be carried out continuously or by clocked heating of the radiator by a defined amount of heat above the boiling point of the substance in its liquid state. By means of heat conduction, the heat fed into the radiator or its heat accumulator or formed therein is transferred to the adjacent substance which is at boiling temperature. As a result, a defined amount of heat is supplied to the substance at the boiling point. Knowing the amount of heat required to convert a quantity of substance at the boiling point into its gas phase evaporates from the substance at the boiling point a quantity of substance corresponding to the additional quantity of heat introduced, which is then a dose of the substance to be fed to the machine in operation. This method makes use of the fact that the heat transfer from the radiator or its heat store to an adjacent boiling liquid by several orders of magnitude is better than the heat transfer to an adjacent gas. For this reason, it is irrelevant for the accuracy of a metering of the gaseous substance whether the heating element is immersed in the boiling liquid or partially protrudes from it, the latter, for example, after a portion of the substance has been consumed.

When dosing, according to which a certain amount of substance is to be dosed per unit of time, it is advisable to take the level into account in the sequence of the heating impulses. A specific amount of ferrocene (ferrocene mass) is assigned to each heating pulse, so that the operational level can be determined by counting the heating pulses and used as a correction variable.

The heat storage capacity of the radiator or its heat store is used primarily to generate small and very small quantities of the required gaseous substance. The radiator can be activated, for example, in a predetermined cycle. The heating impulses carried out can be so short that the radiator heats up, but the heat generated is not transferred to the substance in the boiling state during the duration of the heating impulse. A heat transfer to the adjacent boiling liquid then takes place with a certain time delay. As a result of the heat-conducting connection between the heating element or its heat accumulator and the boiling liquid, the heat generated in the heating element flows out to the boiling liquid based on the principle that heat transfer takes place from the higher energy level to the lower one. From this, a corresponding amount of substance is converted into its gaseous state in accordance with the amount of heat that has flowed in. A timing of the control of the radiator or heaters for producing the gaseous substance takes place according to an embodiment with such a cycle, in which the time interval between two heating pulses is dimensioned such that essentially all of the heat generated in the heating body in a heating cycle to the boiling liquid is released and the radiator or its heat accumulator has its initial temperature again at the beginning of the next heating pulse, namely that of the liquid.

As already mentioned, the heating element can be controlled according to a predetermined time cycle in order to provide a dose of the gaseous substance at intervals specified by the time cycle during an operating cycle of the machine. Such a control is particularly suitable when operating machines, for example internal combustion engines, which are only exposed to slight dynamic changes. Likewise, it is possible to control the radiator (s) provided for the production of the gaseous substance as a function of the operating status data of the machine, for example the internal combustion engine, or to adapt a clocked control to the determined and thus current operating status data.

Resistance heating elements with a positive, non-linear temperature coefficient, in particular so-called PTC resistance heating elements, are particularly suitable as the heating element for introducing the heat required to generate a certain amount of the gaseous substance. Such resistance heating elements have an exponentially increasing resistance above a defined response temperature, which corresponds to the Curie temperature, while such resistance heating elements have a negative temperature coefficient below the response temperature and the resistance does not increase or increases only insignificantly despite the increasing temperature up to the Curie temperature. The response temperature depends on the material. Depending on the choice of material, the maximum heating temperature of such a resistance heating element can thus be set using the response temperature. Overheating of the heating elements and also the material to be heated can be avoided. When using ferrocene, which is to be kept at its boiling temperature of around 249 ° C at an ambient pressure of 1 bar by means of such a PTC resistance heating element and with which resistance heating element a defined amount of heat for generating the desired dose of gaseous ferrocene in the boiling is also generated by appropriate energization Ferrocene is introduced, it will be conveniently equipped with a response temperature of about 270 - 290 ° C. It is also possible to use one or more PTC radiators with a response temperature 249 ° C, with which the liquid ferrocene is kept at its boiling temperature. One or more further PTC radiators with a higher response temperature can then be arranged to be immersed in the boiling liquid together with the aforementioned radiators in order to generate the ferrocene gas dose required in each case.

An advantageous embodiment of the method is obtained if only a small proportion of this is kept at its boiling point from a supply of the substance in liquid and / or solid form. This not only has the advantage that the system is ready for operation more quickly, but that it can also be operated with less energy consumption. If ferrocene is used as a substance to be metered in gaseous form, it makes sense to store the ferrocene in its solid form in a storage container - a reactor. In the reactor, for example, a boiling chamber is formed by a vertically extending tube, within which the heating element or elements are arranged for keeping the liquid ferrocene therein at its boiling temperature and for producing the required ferrocene gas cans. The one or more radiators are expediently arranged axially in such a tube and are therefore concentrically enclosed by the tube. The gap located between the radiator (s) and the inner wall of the tube then represents the actual boiling chamber. A boiling chamber formed in this way is in fluid communication with the further supply of the substance inside the reactor. A design is expedient in which such a tube extends with its lower end into a collector, in which the substance brought into its liquid state, such as ferrocene, from the solid state of the reactor - the storage space - flows in. For this purpose, one or more further heating devices, which can also be designed as PTC resistance heating elements, for example, are arranged in the storage space of such a reactor. When using PTC resistance heating elements, it is expedient to use those which have a response temperature which is somewhat above the melting temperature of the solid material. When using ferrocene, whose melting temperature is around 173 ° C, the PTC resistance elements can have a response temperature of around 190 - 200 ° C. Taking advantage of the Characteristic defined by the response temperature of these PTC resistance heating elements, by means of which heating beyond the response temperature does not exist or is virtually non-existent, does not require any further components, such as thermostats or the like, which are otherwise necessary for temperature control.

In the case of chambering the reactor in the manner described above, it is expedient if the tube forming the chamber has poor thermal conductivity and thus serves as a thermal insulator between the higher temperature in the boiling chamber and the lower temperature in the storage room. With such a configuration, it can be assumed with a clocked activation of the heating element to maintain the boiling temperature or to release the desired gaseous substance quantities that after a heating pulse, the PTC resistance heating element, heated to 290 ° C or 300 ° C, for example, will reach the boiling temperature of the liquid substance cools down. Depending on the operating pressure, which corresponds to the ambient pressure, the boiling temperature is higher or lower. If the boiling temperature is 249 ° C when using ferrocene, it decreases with a decrease in the surrounding pressure. If the method is carried out in a motor vehicle, such a situation arises regularly when the motor vehicle is at appropriate heights. The boiling temperature lowered at such a reduced operating pressure can be determined, for example, by a thermocouple. The boiling temperature can also be determined using the PTC resistance heating element. After a heating pulse, it then cools down. The heating pulses are typically spaced apart from one another to such an extent that this state has occurred. Consequently, the resistance of the PTC resistance heating element can be measured before a heating pulse and the boiling temperature can be determined via the resistance. This can be useful for adjusting the ferrocene mass metering. The temperature determined before such a heating pulse can also be calculated using the gradient between the PTC heating element and the boiling liquid. The determined boiling temperature can also be evaluated by comparing current boiling temperature values with previous measurements. To produce the desired dose of the gaseous substance, for example, a single PTC heating element can be used, which is arranged in the boiling chamber and is continuously energized. The aforementioned properties of a PTC resistance heating element which do not allow any further heating at a certain predefined temperature are used here. In such a case, the PTC heating element will expediently be chosen so small that the continuous amount of gaseous substance corresponds to that which is required. With such a configuration, continuous metering takes place.

The method described and the device described can be used in numerous different applications, in which, in particular, small doses of a gaseous substance are to be fed to a machine in operation. Such a machine can, for example, also be a packaging machine with which small doses of the metered substance are filled into a test tube, for example. In such a case, the packaging or filling machine represents the machine in operation. Only for further explanation of the method and the device, in the context of these statements, reference is made, for example, to metering a gaseous additive for supply into the combustion chamber of an internal combustion engine. The above-described method can also be used for dosing substances which are gaseous under ambient conditions and which are cooled and / or pressurized to carry out the method in order to bring this substance into its liquid state and to keep it at boiling temperature.

The invention is described below using an exemplary embodiment with reference to the accompanying figures. Show it:

1 shows a schematic longitudinal section through a reactor for generating a gaseous substance for supply to a machine in operation,

Fig. 2: a partial cross section through the lower region of the reactor of Figure 1 and

3: shows a schematic representation of a further device for providing and dosing a substance in the gas phase.

In the exemplary embodiment shown, a reactor 1 serves to store a solid substance, namely ferrocene 2 as an additive, which, in its gaseous state, is fed to the combustion chamber of an internal combustion engine (not shown). The reactor 1 serves both for storing ferrocene and for producing gaseous ferrocene cans as part of a metering of the gaseous ferrocene. The reactor 1 is insulated from the outside in order to avoid disturbing inflows and outflows of heat. The reactor 1 is chambered by a central square tube 3, namely in a storage space 4 located outside the tube 3 and in a boiling chamber 5 enclosed by the tube 3. The tube 3 itself consists of a poorly heat-conducting material and thus serves as a thermal insulator between the boiling chamber 5 and the storage space 4. On the outside of the tube 3, a plurality of radiators 6, 6 'are arranged circumferentially distributed at a certain distance from the outer surface of the tube 3. The radiators 6, 6 'are PTC resistance heating elements with a response temperature of approximately 190-200 ° C. The radiators 6, 6 "serve to liquefy the ferrocene 2 originally present in solid form in the reactor 1. FIG. 1 shows the reactor 1 a short time after it has been started up, so that the heating elements 6, 6 'already have a certain proportion of the solid The present ferrocene 2 has been heated above its melting point and has thus been liquefied The liquid ferrocene is identified in FIG.

Another PTC heating element 8 is arranged inside the tube 3. The radiator 8 is designed for higher heating than the radiators 6, 6 '. The response temperature of the radiator 8 is approximately 270-290 ° C. The heater 8 is arranged centrally in the tube 3. The heater 8 is used to heat the ferrocene located in the boiling chamber 5 in its liquid state to its boiling temperature and to keep the ferrocene in the boiling chamber 5 at its boiling temperature. The boiling ferrocene is in figure 1 marked with the reference number 9. Likewise, the radiator 8 is used to introduce a defined amount of heat into the boiling ferrocene 9 in order to convert a corresponding amount of ferrocene into its gaseous state of aggregation in accordance with the amount of heat introduced or in proportion to it, which amount of gaseous ferrocene then represents the additive dose to be fed to the combustion chamber of the internal combustion engine.

The tube 3 with the radiators 6, 6 'and 8 arranged thereon is inserted centrally into the reactor 1 and held by a cover 10 which closes the top of the reactor 1. The reactor 1 is provided in an arrangement such that the tube 3 has a vertical orientation. The tube 3 engages with its lower end in a tapered section of the reactor 1, which is designated as the collector 11. The tube 3 also serves on the top side for discharging the ferrocene gas formed and for feeding it into a feed line 12 for feeding the ferrocene gas into the combustion chamber. For this purpose, the supply line 12 can be connected to the suction side of the air supply. Such a suction line is shown schematically in FIG. 1 with reference number 13. The supply line 12 has on the outside a PTC resistance heating element 14 which surrounds the supply line 12 in a cuff-like manner in order to avoid back condensation.

When starting the internal combustion engine, the radiators 6, 6 ', 8 and 14 are energized at the same time. The radiators 6, 6 'with their response temperature of 190-200 ° C ensure a melting of a certain amount of ferrocene initially present in solid form. Correspondingly, the radiator 8 is energized. Since the boiling chamber 5 is in liquid connection with the storage space 4 through the collector 11, the same liquid level is inside and outside the tube 3. In order to form the boiling chamber as high as possible within the tube 3, the radiators 6, 6 ′ extend beyond the ferrocene level 15 within the storage space 4 of the reactor 1.

The heater 8 also first heats the ferrocene present in solid form within the boiling chamber 5 when the internal combustion engine is started up, in order to liquefy it. Due to the higher speaking temperature of the radiator 8, the ferrocene located in the boiling chamber 5 is heated to its boiling temperature of 249 ° C. at normal pressure of 1 bar. If other ambient pressure conditions exist, the boiling temperature is either lower (at lower ambient pressure) or higher (at higher ambient pressure). The heating element 8 is controlled accordingly in order to keep the ferrocene 9 in the boiling chamber 5 at this temperature. In order to generate a gaseous dose of ferrocene, the heating element 8 in the embodiment shown is heated in a predetermined cycle above the boiling temperature of the ferrocene in order to convert a defined amount of ferrocene into its gaseous state. The internal combustion engine to which the gaseous ferrocene is to be fed is a stationary internal combustion engine which is not subject to major fluctuations in the operating state. It is therefore sufficient in the exemplary embodiment shown if a defined dose of ferrocene gas is introduced into the suction line 13 at regular intervals. As a result of mixing and distribution with the suction air, several combustion cycles of the internal combustion engine can be supplied with a single dose of ferrocene gas. In the illustrated embodiment, the radiator 8 is energized every 10 minutes for a period of about 2 seconds. As a result of the energization, the heating element 8 heats up according to the energization parameters and generates a quantity of heat corresponding to its characteristic. The amount of heat generated flows successively to the boiling ferrocene liquid 9 surrounding the radiator 8, with the result that an amount of ferrocene corresponding to the amount of heat given off is converted into its gas phase. This process is symbolized in FIG. 1 by the meandering lines in the boiling chamber 5. These lines symbolize the ascending gaseous ferrocene. As a result of the excess pressure which arises during the evaporation, the ferrocene vapor formed automatically flows off via the feed line 12 and into the suction line 13. The amount of ferrocene gas required is very small. The amount of ferrocene gas flowing out of the feed line 12 and flowing into the suction line 13 is correspondingly small. As a result of the disproportionately greater proportion of air volume in the suction line 13, the ferro-gas is very strongly diluted. This process is desired and has Consequence that due to the cooling of the ferrocene gas within the suction line 13, the ferrocene is brought back into its solid form, but due to the strong dilution into microscopic particles, as this is schematized in the elevation within the suction line 13 in FIG is shown. These particles are ferrocrystals, which are denoted in FIG. 1 by the reference symbol FK. These microscopic particles FK are in turn easily transported with the air flow flowing in the suction line 13 and fed to the combustion chamber of the internal combustion engine. This effectively prevents clogging of elements in the suction line due to receding ferrocene.

FIG. 2 shows a cross section of the tube 3 with the heating element 8 arranged therein. It is clear from this illustration that the boiling chamber 5 is ultimately an annular gap between the heating element 8 and the inner wall of the tube 3. The clear width of the annular gap can be provided to be relatively small, so that the amount of ferrocene in the boiling chamber is also correspondingly small. With a correspondingly low energy requirement, the ferrocene located in the boiling chamber 5 can therefore be heated and in particular kept at its boiling temperature. The small amount of ferrocene in the boiling chamber 5 also means that the reactor 1 is ready for operation quickly, within a few seconds, and can then be operated with the required additive dose immediately after the internal combustion engine has been started up.

In the illustrated embodiment, the radiator 8 is designed as a PTC resistance heating element. By means of the characteristic curve and in particular the mass and the thermal properties of this PTC element, a defined amount of heat can be generated in accordance with the applied energization parameters, for example the energization time, temporarily stored in the PTC element itself and released to the surrounding boiling ferrocene liquid 9. As previously stated, the heat storage capacity of the radiator 8 is used. Since the heat transfer between the surface of the radiator 8 and the boiling ferrocene liquid adjacent to it is several orders of magnitude higher than that Heat transfer to a surrounding gas, such as in the area of the radiator 8, which lies above the ferrocene level 15, can be assumed that the entire amount of heat generated is transferred to the boiling ferrocene liquid 9 within very narrow tolerance limits and not or only insignificantly and in not significant extent to the gas located above the liquid level. The activation of the radiator 8 is timed at a time interval - as mentioned - in which it is ensured that the heat generated by the preceding heating pulse has been completely or essentially completely given off to the boiling ferrocene liquid. When determining the amount of heat generated by the heating element 8, it can then be assumed that the heating element 8 is at boiling temperature at the beginning of a heating pulse.

In the described exemplary embodiment, the high dilution occurring in the suction line 13 skillfully uses the transition of the gaseous substance metered in a small amount into microscopic additive particles, so that the additive is ultimately introduced into the combustion chamber in the form of solid, microscopic particles. Additive particles that remain in the supply line 12 or the suction line 13 when the internal combustion engine is taken out of operation are readily absorbed by the sucked-in air flow when the internal combustion engine is started up again and supplied to the combustion chamber. This also ensures that the additive feed system is ready for operation quickly.

FIG. 3 shows a further device 16 for providing a gaseous substance for metering the same. The device 16 is used to provide an additive in its gas phase for supplying the additive gas into the combustion chamber of an internal combustion engine and comprises a reactor 17, which in the exemplary embodiment shown is heat-insulated. Ferrocene 18 is present in the reactor 17 as an additive in its solid state of matter. This has previously been introduced into the reactor 17 in its liquid phase, and the ferrocene, which is now present in its solid state of matter in the reactor, has crystallized by cooling. The reactor 17 is in its lower section tapered downward to form a fluid trap. The reactor 17 is connected via an outlet 19 to an additive line 20, which opens into the air intake line of a diesel engine in a manner not shown. In the area of the outlet 19 of the reactor 17, a throttle 21 is arranged as a metering device. The throttle 21 is manually adjustable, it being provided in the device 16 that it is operated with a constant throttle setting.

The device 16 also has a heating device 22. The heating device 22 comprises a rod-shaped heating element 23 which extends into the ferrocene 18 in solid form. The heating device 22 is mounted with its heating element 23 on the reactor 17, as long as the ferrocene introduced into the reactor 17 in its liquid phase has not yet, at least not completely, solidified. The heater 23 is designed in the illustrated embodiment as a resistance heater and can be energized via an electrical connection cable 24. The heater 23 of the device 16 shown in FIG. 3 is designed so that it has its greatest heating output in the region of its lower free end section 25.

Alternatively, the reactor 17 can also be filled with powdered ferrocene. This then melts when the heater is started up for the first time and crystallizes out of the liquid phase after the heater has been shut down. With this configuration, the heating device can ultimately be installed at any time.

When the heating device 22 is in operation, ferrocene located in the region of the end section 25 of the radiator 23 is heated above its melting temperature of 173 ° C, brought to a boil by further heating, so that the ferrocene 18, which is initially in its solid state, ultimately ends up in its gas phase has been transferred. As the heating increases, a ferrocene liquid jacket will gradually form around the heating element 23, so that the heat transfer from the heating element 23 into the ferrocene 18, which is in solid form, is favored. The reactor 17 is designed so that the ferrocene 18 located in the region of the reactor walls also passes through the heater 23 can be melted. With increasing ferrocene consumption, the ferrocene level inside the reactor 17 drops. In order to be able to melt all of the ferrocene 18 located in the reactor 17, the reactor 17 is tapered in the region of its base to form the liquid trap described above.

The device 16 shown in FIG. 3 is in operation. Around the radiator 23, the ferrocene 18 in the solid state in the reactor 17 has been heated above its melting point, so that a liquid jacket of molten ferrocene has formed. The ferrocene evaporating from the liquid bath in its gaseous state is shown schematically by the meandering arrows in this figure. The escape of the ferrocene gas formed from the liquid jacket naturally also takes place via pathways within the still solid ferrocene 18. An internal pressure is formed inside the reactor 17, which can be approximately 2.5-3.0 bar.

As a result of the vaporization of the ferrocene, a vapor overpressure forms within the reactor 17, so that the ferrocene gas formed flows automatically out of the outlet 19 and through the throttle 21 into the additive line 20. The throttle 21 is set in such a way that the outflowing additive quantity is sufficient for the intended additivation of the fuel-air mixture with an average fuel consumption over the service life of the diesel engine. Therefore, if such a fixed throttle is provided, such as throttle 21, it will also be set differently in different motors depending on its use.

The reactor 17 expediently has a pressure sensor for detecting the internal pressure in the reactor 17 during operation of the heating device 22. Depending on the detected pressure, which is expediently kept largely constant, the heating device 22 is activated in order to evaporate either more or less ferrocene into its gas phase.

The reactor 17 may also have a pressure relief valve, which ultimately serves as a safety valve.

Instead of providing a fixed throttle, as provided in the device 16, a controllable valve, for example a clock valve or the like, can also be provided for metering the ferrocene gas. In such a case, the additive dosage will be made dependent on the current engine power or the current fuel consumption. For this, however, it is necessary to collect the relevant data. For this reason, a metering device with a fixed throttle will be preferred for retrofitting existing systems.

The heating element 23 of the heating device 22 is led into the area of the outlet 19 and is located in particular in the vicinity of the throttle 21. When the heating element 23 is in operation, the throttle 21 is also heated, so that ferrocene gas, which is produced by switching off the heating device 22, for example as a result of a shutdown of the diesel engine in the region of the throttle 21, and condenses back to solid ferrocene, is readily gasified again when the heating device is started up again, and thus the throttle 21 is freed of the condensate.

LIST OF REFERENCE NUMBERS

1 reactor 2 ferrocene, solid 3 tube 4 storage room 5 boiling chamber, 6 'radiator 7 ferrocene, liquid 8 radiator 9 ferrocene, boiling

10 lids

11 collectors

12 supply line

13 suction line

14 radiators

15 ferrocene mirror

16 device

17 reactor

18 ferrocene

19 exit

20 Additive line

21 choke

22 heating device

23 radiators

24 connection cables

25 end section

FK ferrocene crystal

Claims

claims

1. A method for dosing a substance, in particular small quantities thereof, for feeding the same to a machine in operation, for example an internal combustion engine, in which method the substance (2, 18) to be dosed is brought into its gaseous state, characterized in that the substance (2, 18) is liquefied before being converted into its gaseous state before it is brought into its gaseous state for metering in the course of further heating.

2. The method according to claim 1, characterized in that the substance (2, 18) is stored in its solid state and only a part of the solid substance (2, 18) liquefied and in its to provide the required amount of gaseous substance Gas phase is transferred.

3. The method according to claim 1 or 2, characterized in that the gas formed is stored in a reactor (17) and metered by means of a throttle (21) or a valve.

4. The method according to claim 1 or 2, characterized in that the substance for the process of dosing from its liquid state of aggregation by heat using at least one electric heater (8) is converted into its gaseous state of aggregation and a dosage by the amount of each produced gaseous substance is controlled by - the substance in its liquid state being kept at boiling temperature, - using a defined heat storage capacity of the radiator (8) or an associated heat accumulator, which also has at least one radiator also having the temperature of the liquid substance (9) (8) Current flow parameters are heated depending on a defined amount of heat above the boiling point of the substance and - The defined heat fed into the radiator (8) and / or its heat accumulator is transferred by heat conduction to the substance (9) which is at the boiling point and thereby a quantity of the substance (9) proportional to the quantity of heat transferred is converted into its gaseous state, - The amount of substance brought into the gaseous state is a dose of the substance to be fed to the machine in operation.

5. The method according to claim 4, characterized in that for the dosing of individual doses of the heating element (8) is heated in a clocked manner in order to generate heating pulses.

6. The method according to claim 4, characterized in that for dosing individual substance doses, the radiator for generating heating pulses is heated as a function of determined operating status data of the machine in operation.

7. The method according to any one of claims 4 to 6, characterized in that with a first radiator, the substance in its liquid state is kept at its boiling temperature and that by means of a second radiator, the substance in its liquid state is supplied with the heat necessary for evaporation becomes.

8. The method according to any one of claims 4 to 7, characterized in that the substance to be dosed is stored in its solid state and at the beginning of an operating cycle of the machine only a small part of the stock is first brought into its liquid state and then brought to the boil before dosing can begin.

9. Use of the method according to one of claims 4 to 8 for loading a fuel-air mixture to be supplied to a combustion chamber of an internal combustion engine with an additive present in the gas phase as the substance to be metered.

10. Use according to claim 9, characterized in that an iron-containing metal-organic compound is used as the substance to be metered.

11. Use according to claim 10, characterized in that ferrocene is used as the substance to be metered.

12. Device for dosing a substance, comprising a reactor (1) for storing the substance (2) in its solid state, in which reactor (1) the substance (2) is brought into its gas phase, characterized in that - Reactor (1) has a chamber and has a boiling chamber (5) and a storage space (4), the boiling chamber (5) being in fluid communication with the storage space (4) - that at least one in the boiling chamber (5) electrical contact heating element (8) immersed therein is arranged with a defined heat storage capacity, which heating element (8) is designed to heat substance (9) therein to boiling temperature to provide a gaseous substance dose above the boiling temperature, and - in that Storage room (4) one or more heaters designed to transfer the substance (2) stored therein in its solid state into its liquid state devices (6, 6 ') are arranged.

13. The apparatus according to claim 12, characterized in that the boiling chamber (5) in the reactor (1) is enclosed by a vertically arranged tube (3), the upper end of which is the exit for the gaseous substance formed in the boiling chamber (5) the reactor (1) forms.

14. The apparatus according to claim 13, characterized in that the radiator (8) is arranged concentrically within the tube (3) and between the radiator (8) and the inside of the tube an annular gap for receiving the to be kept at the boiling temperature Fabric (9) is arranged.

15. The apparatus of claim 13 or 14, characterized in that the tube (3) extends with its lower end into a collector (11) into which the liquid (7) brought into the storage space (4) in its liquid state of aggregation flows.

16. The device according to one of claims 12 to 15, characterized in that the heating element (8) immersed in the boiling chamber (5) is a resistance heating element with a positive, non-linear temperature coefficient above its response temperature, the heating element (8) being designed, that the response temperature is the temperature of the maximum desired heating of the radiator (8).

17. The apparatus according to claim 16, characterized in that the radiator is a PTC resistor.

18. Device according to one of claims 12 to 17, characterized in that two or more radiators are arranged in the boiling chamber.

19. Device according to one of claims 12 to 18, characterized in that in the storage space (4) of the reactor (1) a plurality of individual contact heaters (6, 6 '), advantageously resistance heating elements with a positive, non-linear temperature coefficient above their response temperature, wherein the radiators (6, 6 ') are designed so that the response temperature is the temperature of the maximum desired heating of the respective radiator.

20. Device according to one of claims 12 to 19, characterized in that the or the contact heater arranged in the boiling chamber have a structuring which increases the contact surface.